Acylated pyrimidine nucleosides for treatment of systemic inflammation and inflammatory hepatitis

ABSTRACT

Pyrimidine nucleotide precursors including acyl derivatives of cytidine, uridine, and orotate, and uridine phosphorylase inhibitors, and their use in enhancing resistance to sepsis or systemic inflammation are disclosed.

This is a Divisional of application Ser. No. 08/266,897, filed Jul. 1,1994, now abandoned, which is a continuation-in-part application ofcopending U.S. application Ser. No. 158,799, filed Dec. 1, 1993, nowabandoned, which in turn is a continuation-in-part application ofcopending U.S. application Ser. No. 987,730, filed Dec. 8, 1992, nowabandoned, which in turn is a continuation-in-part application of U.S.application Ser. No. 438,493, filed Jun. 26, 1990, now abandoned, whichin turn is a continuation-in-part application of U.S. application Ser.No. 115,929 filed Oct. 28, 1987 now abandoned. All of these applicationsare hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates generally to pyrimidine nucleotide precursorsincluding acyl derivatives of cytidine, uridine and orotate, and to theprophylactic and therapeutic uses of these compounds. The invention alsorelates to the administration of these compounds, alone or incombinations, with or without other agents, to animals. These compoundsare capable of enhancing resistance of an animal to bacterial endotoxinand other inflammatory stimuli, and inflammatory mediators.

BACKGROUND OF THE INVENTION

Sepsis, also referred to as sepsis syndrome, is a consequence of seriousinfection by bacteria, fungi, or viruses. Sepsis accounts for tens ofthousands of deaths in the United States every year; it is a leadingcause of death of patients in surgical intensive care units.

Sepsis is an inflammatory disorder in which endogenous cytokines andother bioactive molecules, produced or released in response to aninflammatory stimulus such as bacterial endotoxin (a component of thecell wall of gram-negative bacteria), cause various symptoms includingfever, neutropenia, blood coagulation disorders, hypotension, shock, andorgan damage.

Sepsis (or in its more severe form, septic shock), is one example of abroader class of disease called the "Systemic Inflammatory ResponseSyndrome" (SIRS), which is an organism's reaction to inflammatorystimuli such as endotoxin (which can be present in the bloodstreamwithout bacteremia, e.g. due to leakage of endotoxin from gram-negativebacteria into the circulation from a localized infection or from theintestine); SIRS can also be triggered by gram-positive bacteria, fungi,viruses, and can also be a consequence of autoimmune disorders oradministration of therapeutic inflammatory cytokines.

Current treatment of SIRS involves circulatory and respiratory support,but does not directly address improvement of tissue resistance toinflammatory stimuli such as endotoxin, or inflammatory mediators.

Monoclonal antibodies for neutralizing endotoxins or mediators of itsphysiologic effects are under development. However, it is expensive orimpractical to use antibodies as prophylaxis in susceptible patients,prior to the onset of symptoms of endotoxin poisoning. Moreover, it isdifficult to determine which patients are likely to benefit fromantibody treatment, since the time required to culture and identifyinfectious organisms often exceeds the time limit for implementation ofeffective therapy. Similar problems have been encountered in attempts touse receptor antagonists of specific inflammatory meidators likeinterleukin-1.

Endotoxin toxicity is in part mediated by endogenous cytokines and otherbioactive molecules released from macrophages, Kupffer cells (sessilemacrophages in the liver) and other cell types in response to endotoxin.Among the most significant of these mediators are tumor necrosis factor(TNF) and interleukin-1 (IL-1). Others include platelet activatingfactor (PAF), interleukin-6, and leukotrienes and other arachidonic acidderivatives. Administration of these cytokines or mediators results insymptoms similar to at least some of those elicited by endotoxin. Agentsor pathological conditions other than bacterial endotoxin can result inelevated production or activity of (or sensitivity to) TNF or IL-1,resulting in tissue damage. Such conditions include infection withgram-positive bacteria, viruses or fungi, or liver damage. Inflammatorycytokines can produce tissue damage if present in excess, but whenelicited in moderate amounts, they are important in the defense againstinfectious organisms or viruses. For example, antibodies to TNF canreduce toxicity of an administered dose of endotoxin (by blocking thenegative effects of TNF elicited by the endotoxin), but can have adeleterious effect in the case of some bacterial infections, convertinga sublethal state of infection into an overwhelming lethal infection(Havell, J. Immunol., 1987, 139:4225-4231; Echtenacher et al., J.Immunol., 1990 145:3762-3766). Thus, there are inherent problems withstrategies for treating sepsis syndrome or SIRS with agents whichdirectly inactivate inflammatory cytokines.

The liver is a major site for clearance or detoxification of endotoxin(Farrar and Corwin, Ann. N.Y. Acad. Sci., 1966 133:668-684) andinflammatory proteins like TNF; conversely, the liver is susceptible todamage by endotoxin and its mediators. Liver damage from manyoriginating causes (e.g. carbon tetrachloride, choline deficiency, viralinfection, Reye's syndrome, alcohol) is in part mediated by bacterialendotoxin or mediators elicited by endotoxin even when symptoms ofsystemic sepsis are not present (Nolan, Gastroenterology, 1975,69:1346-1356; Nolan, Hepatology, 1989, 10:887-891). Hepatic toxicity isdose-limiting in patients receiving intentional injections of endotoxinfor possible efficacy in treating cancer (Engelhardt et al., CancerResearch, 1991, 51:2524-2530). The liver has been reported to be thefirst vital organ displaying pathological alterations in septic shock(Kang et al., J. Histochem. Cyctochem., 1988 36:665-678). Moreover,hepatic dysfunction occurs in the early stages of sepsis and mayinitiate sequential organ failure (Wang et al., Arch. Surg., 1991,126:219-224).

The liver is important in regulating the sensitivity of an animal toendotoxin. Various treatments which impair liver function or metabolism,such as poisoning with lead acetate, cycloheximide, Actinomycin D orgalactosamine can increase the sensitivity of animals to endotoxin orTNF, in some cases by several orders of magnitude.

Galactosamine-induced liver damage is unique in that it is readilyreversible during a period before cell death occurs. Galactosamineselectively depletes hepatic uridine nucleotides, by locking them intoUDP-hexosamines that are not converted back into free nucleotides. Thiscan lead to liver damage if the depletion of uridine nucleotides issufficiently prolonged, due to impairment of RNA and protein synthesis.The biochemical deficiency induced by galactosamine is readily reversedby administration of uridine, which replenishes the uridine nucleotidestrapped by the galactosamine. Thus, administration of uridine shortlybefore or after administration of galactosamine attenuatesgalactosamine-induced hepatic damage and consequently restoressensitivity to endotoxin toward normal values (Galanos et al., PNAS,1979, 76:5939-5943).

Similarly, endotoxin hypersensitivity in mice deliberately treated withthe rodent hepatotoxin TCDD was partially reversed by administration ofuridine (Rosenthal et al., Toxicology, 1989 56:239-251).

However, in contrast to these situations wherein uridine partiallyreversed experimentally-reduced resistance to endotoxin, uridine wasreported to have no protective effect in normal mice challenged withendotoxin (Markley et al., J. Trauma 1970, 10:598-607), i.e., it did notresult in greater-than-normal resistance to endotoxin.

Uridine, cytidine, and orotate have been tested for effects on liverfunction in hepatic disorders and in experimental models, with mixedresults. Shafer and Isselbacher (Gastroenterology, 1961, 40:782-784)reported that daily intravenous infusion of 25 to 100 milligrams ofcytidine and uridine, for 3 to 7 days, to patients with hepaticcirrhosis had no effect on clinical status. Orotic acid added to ratdiet in a concentration of 1 percent results in fatty infiltration ofthe liver (von Euler et al, J. Biol. Chem., 1963, 238:2464-2469); oroticacid administered by intraperitoneal injection reduced liver damage inrats treated with carbon tetrachloride, dichloroethane, DDT, and9,10-dimethyl-1,2-benzanthracene (Pates et al., Farmakol Toksikol.,1968, 31:717-719). Lysine-orotate potentiated the toxicity ofhepatotoxic extracts from the mushroom Amanita Phalloides; sodiumorotate and orotic acid had no effect on Amanita extract toxicity(Halacheva et al., Toxicon, 1988, 26:571-576). Orotic acid has beenadministered clinically to humans for treatment of neonatalhyperbilirubinemia and for improving recovery from myocardial infarction(O'Sullivan, Aust. N.Z. J. Med., 1973, 3:417-422). Orotate is not wellabsorbed after oral administration, in part due to poor solubility.

Hata et al. (U.S. Pat. Nos. 4,027,017 and 4,058,601) disclose thaturidinediphosphate and uridinediphosphoglucuronic acid reduce bloodalcohol content and inhibit accumulation of neutral lipids in the liverafter administration of ethanol.

Clinical trials involving the administration of uridine (e.g. for thepurpose of attenuating host toxicity of the antineoplastic drug5-fluorouracil) have been complicated due to the biological propertiesof uridine itself. Uridine is poorly absorbed after oral administration;diarrhea is dose limiting in humans (van Groeningen et al., Proceedingsof the AACR, 1987, 28:195). Parenteral administration of uridinerequires use of a central venous catheter (with consequent discomfortand risk of infection), since phlebitis was a problem in early clinicaltrials when uridine was administered via a brachial venous catheter (vanGroeningen et al. Cancer Treat Rep., 1986, 70:745-50).

Administration of acyl derivatives of uridine and cytidine, which arereadily absorbed from the gut into the bloodstream, and which are thenhydrolyzed to yield free uridine or cytidine in the circulation,overcome the problem of poor oral absorption of the free nucleosides(U.S. patent applications Ser. No. 438,493, 115,929, and 903,107, herebyincorporated by reference).

OBJECTS OF THE INVENTION

It is a primary object of the invention to provide therapeutic andprophylactic agents which are effective in improving survival and inpreventing tissue damage from systemic inflammatory response syndrome,including sepsis.

It is a primary object of this invention to provide a family ofcompounds which effectively enhance resistance to systemic inflammation.Administration of these compounds to an animal before, during or afterexposure to endotoxin or other inflammatory stimuli, prevents or treatsthe effects of systemic inflammation.

It is a further object of this invention to provide a family ofcompounds for the treatment of a variety of disorders involvinginflammatory stimuli or inflammatory cytokines in their etiology.

It is a further object of this invention to provide a family ofcompounds to improve survival or physiological functions in animalssubjected to endotoxin poisoning or other systemic inflammatorydisorders.

It is a further object of the invention to provide family of compoundsto treat or prevent inflammatory hepatitis.

It is a further object of the invention to provide compounds which canbe administered orally or parenterally.

SUMMARY OF THE INVENTION

These and other objects of the invention are achieved by precursors ofpyrimidine nucleotides such as orotic acid or its salts, uridine,cytidine, or prodrug derivatives of these agents including acylderivatives or phosphate esters, which can be administered to animals,including mammals such as humans. The administration of these compoundsalone, or in combination, is useful in treatment or prevention ofconsequences of systemic inflammation. Systemic inflammation is causedby infection with bacteria, fungi, or viruses, constituents of bacteria,fungi or viruses, e.g. endotoxin, polysaccharides or viral proteinsrespectively, by inflammatory mediators, or as a consequence ofautoimmune disorders.

Thus, the compounds of the invention, alone or in combination, areuseful in the treatment and prevention of sepsis or toxic effects ofinflammatory cytokines; are useful as prophylactic agents in patients atrisk of sepsis e.g. patients undergoing surgical procedures, orafflicted with serious burns or wounds, or immunocompromised as aconsequence of chemotherapy for cancer or other diseases.

An important aspect of this invention is the discovery that pyrimidinenucleotide precursors such as orotate, uridine, or cytidine, and acylderivatives of such compounds, have unexpected therapeutic properties.

One embodiment of the invention involves the use of the compounds andcompositions of the invention in treatment and prevention of toxicityencountered during therapeutic administration of inflammatory cytokines,e.g. for treatment of cancer.

One embodiment of the invention involves the use of the compounds andcompositions of the invention in treatment and prevention ofinflammatory hepatitis.

COMPOUNDS OF THE INVENTION

The compounds useful in enhancing resistance to inflammatory stimuli orinflammatory mediators have the following structures:

In all cases except where indicated, letters and letters with subscriptssymbolizing variable substituents in the chemical structures of thecompounds of the invention are applicable only to the structureimmediately preceding the description of the symbol.

(1) Uridine or an acyl derivative of uridine having the formula:##STR1## wherein R₁, R₂, R₃ and R₄ are the same or different and each ishydrogen or an acyl radical of a metabolite, or a pharmaceuticallyacceptable salt thereof.

(2) Cytidine or an acyl derivative of cytidine having the formula:##STR2## wherein R₁, R₂, R₃ and R₄ are the same or different and each ishydrogen or an acyl radical of a metabolite or a pharmaceuticallyacceptable salt thereof.

(3) An acyl derivative of uridine having the formula: ##STR3## whereinR₁, R₂, and R₃ are the same, or different, and each is hydrogen or anacyl radical of

a. an unbranched fatty acid with 5 to 22 carbon atoms,

b. an amino acid selected from the group consisting of glycine, the Lforms of alanine, valine, leucine, isoleucine, tyrosine, proline,hydroxyproline, serine, threonine, cystine, cysteine, aspartic acid,glutamic acid, arginine, lysine, histidine, carnitine and ornithine,

c. a dicarboxylic acid having 3-22 carbon atoms,

d. a carboxylic acid selected from one or more of the group consistingof glycolic acid, pyruvic acid, lactic acid, enolpyruvic acid, lipoicacid, pantothenic acid, acetoacetic acid, p-aminobenzoic acid,betahydroxybutyric acid, orotic acid, and creatine.

(4) An acyl derivative of cytidine having the formula: ##STR4## whereinR₁, R₂, R₃, and R₄ are the same, or different, and each is hydrogen oran acyl radical of

a. an unbranched fatty acid with 5 to 22 carbon atoms,

b. an amino acid selected from the group consisting of glycine, the Lforms of phenylalanine, alanine, valine, leucine, isoleucine, tyrosine,proline, hydroxyproline, serine, threonine, cystine, cysteine, asparticacid, glutamic acid, arginine, lysine, histidine carnitine andornithine,

c. a dicarboxylic acid having 3-22 carbon atoms,

d. a carboxylic acid selected from one or more of the group consistingof glycolic acid, pyruvic acid, lactic acid, enolpyruvic acid, lipoicacid, pantothenic acid, acetoacetic acid, p-aminobenzoic acid,betahydroxybutyric acid, orotic acid, and creatine.

(5) An acyl derivative of uridine having the formula: ##STR5## whereinat least one of R₁, R₂, or R₃ is a hydrocarbyloxycarbonyl moietycontaining 2-26 carbon atoms and the remaining R substituents areindependently a hydrocarbyloxycarbonyl or hydrocarbylcarbonyl moiety orH or phosphate.

(6) An acyl derivative of cytidine having the formula: ##STR6## whereinat least one of R₁, R₂, R₃ or R₄ is a hydrocarbyloxycarbonyl moietycontaining 2-26 carbon atoms and the remaining R substituents areindependently a hydrocarbyloxycarbonyl or hydrocarbylcarbonyl moiety orH or phosphate.

(7) Orotic acid or salts thereof: ##STR7##

Pharmaceutically-acceptable salts of orotic acid include those in whichthe cationic component of the salt is sodium, potassium, a basic aminoacid such as arginine or lysine, methylglucamine, choline, or any othersubstantially nontoxic water soluble cation with a molecular weight lessthan about 1000 daltons.

8) Alcohol-substituted orotate derivatives: ##STR8## wherein R₁ is aradical of an alcohol containing 1 to 20 carbon atoms joined to orotatevia an ester linkage.

Also encompassed by the invention are the pharmaceutically acceptablesalts of the above-noted compounds.

Advantageous compounds of the invention are short-chain (2 to 6 carbonatoms) fatty acid esters of uridine or cytidine. Particularlyadvantageous compounds are triacetyluridine, triacetylcytidine or saltsof orotic acid.

Inhibitors of Uridine Phosphorylase

As an alternative or adjunct to the above-noted pyrimidine nucleotideprecursors, the following compounds are useful in the invention. Theseagents elevate tissue uridine nucleotide levels by inhibiting catabolismof endogenous or exogenous uridine. Co-administration of uridinephosphorylase inhibitors with pyrimidine nucleotide precursors reducesthe amount of nucleotide precursor required to obtain therapeuticbenefit.

Examples of inhibitors of uridine phosphorylase include but are notlimited to 5-benzyl barbiturate or 5-benzylidene barbiturate derivativesincluding 5-benzyl barbiturate, 5-benzyloxybenzyl barbiturate,5-benzyloxybenzyl-1- (1-hydroxy-2-ethoxy)methyl! barbiturate,5-benzyloxybenzylacetyl-1- (1-hydroxy-2-ethoxy)methyl! barbiturate, and5-methoxybenzylacetylacyclobarbiturate, 2,2'-anhydro-5-ethyluridine, andacyclouridine compounds, particularly 5-benzyl substituted acyclouridinecongeners including but not limited to benzylacyclouridine,benzyloxybenzylacyclouridine, aminomethyl-benzylacyclouridine,aminomethylbenzyloxybenzylacyclouridine,hydroxymethyl-benzylacyclouridine, andhydroxymethyl-benzyloxybenzylacyclouridine. See also WO 89/09603 and WO91/16315, hereby incorporated by reference.

DETAILED DESCRIPTION OF THE INVENTION

The subject invention relates to pyrimidine nucleotide precursorsincluding acyl derivatives of cytidine, uridine, and orotate, and theuse of these compounds and/or uridine phosphorylase inhibitors fortreating or preventing pathological consequences of endotoxin and otherinflammatory stimuli or mediators in animals, including humans.

The invention disclosed herein involves methods for enhancing theresistance of an animal to inflammatory stimuli and mediators. Examplespresented below demonstrate both prophylaxis and treatment of toxicitydue to endotoxin and other inflammatory stimuli. The method of theinvention can be used in conjunction with other methods for treating orpreventing sepsis or systemic inflammation.

A. Definitions The term "pyrimidine nucleotide precursor" as used hereinrefers to a compound which is converted to a pyrimidine nucleotidefollowing administration to an animal. This includes especiallycytidine, uridine, or orotic acid, or prodrugs (including acylderivatives) of these compounds.

The term "acyl derivative" as used herein means a derivative of apyrimidine nucleoside in which a substantially nontoxic organic acylsubstituent derived from a carboxylic acid is attached to one or more ofthe free hydroxyl groups of the ribose moiety of the oxypurinenucleoside with an ester linkage and/or where such a substituent isattached to the amine substituent on the purine ring of cytidine, withan amide linkage. Such acyl substituents are derived from carboxylicacids which include, but are not limited to, compounds selected from thegroup consisting of a fatty acid, an amino acid, nicotinic acid,dicarboxylic acids, lactic acid, p-aminobenzoic acid and orotic acid.Advantageous acyl substituents are compounds which are normally presentin the body, either as dietary constituents or as intermediarymetabolites.

The term "pharmaceutically acceptable salts" as used herein means saltswith pharmaceutically acceptable acid addition salts of the derivatives,which include, but are not limited to, sulfuric, hydrochloric, orphosphoric acids.

The term "coadministered" means that at least two of the compounds ofthe invention are administered during a time frame wherein therespective periods of pharmacological activity overlap.

The term "amino acids" as used herein includes, but is not limited to,glycine, the L forms of alanine, valine, leucine, isoleucine,phenylalanine, tyrosine, proline, hydroxyproline, serine, threonine,cysteine, cystine, methionine, tryptophan, aspartic acid, glutamic acid,arginine, lysine, histidine, ornithine, hydroxylysine, carnitine, andother naturally occurring amino acids.

The term "fatty acids" as used herein means aliphatic carboxylic acidshaving 2-22 carbon atoms. Such fatty acids may be saturated, partiallysaturated or polyunsaturated.

The term "dicarboxylic acids" as used herein means fatty acids with asecond carboxylic acid substituent.

The term "therapeutically effective amount" as used herein refers tothat amount which provides therapeutic effects for a given condition andadministration regimen.

The term "sepsis" as used herein is a systemic inflammatory disorder inwhich endogenous cytokines and other bioactive molecules, produced orreleased in response to an inflammatory stimulus such as bacterialendotoxin (a component of the cell wall of gram-negative bacteria),cause various symptoms including fever, neutropenia, blood coagulationdisorders, hypotension, shock, and organ damage.

The term "inflammatory stimulus" as used herein means an exogenous agentwhich triggers an inflammatory response in an animal. Examples ofinflammatory stimuli include bacteria, fungi, viruses, nonviablefragments or components of bacteria (such as endotoxin), fungi orviruses, or agents which trigger allergic or anaphylactic responses. Inthe case of autoimmune disorders, endogenous elements of a patient'stissues, e.g. particular cellular proteins function as inflammatorystimuli.

The term "mediator" as used herein means endogenous or exogenous (e.g.recombinant polypeptides) bioactive compounds, proteins, or polypeptidesthat typically mediate the biological effects of endotoxin or otherinflammatory stimuli such as fungal polysaccharides. Examples of suchagents include but are not limited to tumor necrosis factor (TNF),interleukin-1 (IL-1), interleukin-6 (IL-6), plasminogen activatorinhibitor (PAI) leukotrienes, elements of the complement cascade, nitricoxide, or platelet-activating factor.

B. Compounds of the Invention

A primary feature of the present invention is the unexpected discoverythat uridine and other pyrimidine nucleotide precursors do in factprotect otherwise normal animals (e.g. animal models in which theorganism has not received a clinically-irrelevant hepatotoxicsensitizing agent like galactosamine or TCDD) from toxicity due tobacterial endotoxin and other inflammatory stimuli which produce tissuedamage through elicitation of endogenous inflammatory mediators.

Tissue uridine nucleotide levels can be increased by administration ofseveral precursors. Uridine and cytidine are incorporated into cellularnucleotide pools by phosphorylation at the 5' position; cytidine anduridine nucleotides are interconvertible through enzymatic amination andde-amination reactions. Orotic acid is a key intermediate in de novobiosynthesis of pyrimidine nucleotides. Incorporation of orotic acidinto nucleotide pools requires cellular phosphoribosyl pyrophosphate(PRPP). Alternatively (or in addition to provision of exogenousnucleotide precursors), availability of uridine to tissues is increasedby administration of compounds which inhibit uridine phosphorylase, thefirst enzyme in the pathway for degradation of uridine. The compounds ofthe invention useful in enhancing resistance to endotoxin orinflammatory mediators include uridine, cytidine, orotate, prodrug formsof these pyrimidine nucleotide precursors, particularly acyl derivativesand phosphate esters, and inhibitors of the enzyme uridinephosphorylase. Compounds of the invention have the following structures:

In all cases except where indicated, letters and letters with subscriptssymbolizing variable substituents in the chemical structures of thecompounds of the invention are applicable only to the structureimmediately preceding the description of the symbol.

(1) An acyl derivative of uridine having the formula: ##STR9## whereinR₁, R₂, R₃ and R₄ are the same or different and each is hydrogen or anacyl radical of a metabolite, provided that at least one of said Rsubstituents is not hydrogen, or a pharmaceutically acceptable saltthereof.

(2) An acyl derivative of cytidine having the formula: ##STR10## whereinR₁, R₂, R₃ and R₄ are the same or different and each is hydrogen or anacyl radical of a metabolite, provided that at least one of said Rsubstituents is not hydrogen, or a pharmaceutically acceptable saltthereof.

The compounds of the invention useful in enhancing resistance toendotoxin include:

(3) An acyl derivative of uridine having the formula: ##STR11## whereinR₁, R₂, and R₃ are the same, or different, and each is hydrogen or anacyl radical of

a. an unbranched fatty acid with 5 to 22 carbon atoms,

b. an amino acid selected from the group consisting of glycine, the Lforms of alanine, valine, leucine, isoleucine, tyrosine, proline,hydroxyproline, serine, threonine, cystine, cysteine, aspartic acid,glutamic acid, arginine, lysine, histidine, carnitine and ornithine,

c. a dicarboxylic acid having 3-22 carbon atoms,

d. a carboxylic acid selected from one or more of the group consistingof glycolic acid, pyruvic acid, lactic acid, enolpyruvic acid, lipoicacid, pantothenic acid, acetoacetic acid, p-aminobenzoic acid,betahydroxybutyric acid, orotic acid, and creatine.

(4) An acyl derivatives of cytidine having the formula: ##STR12##wherein R₁, R₂, R₃, and R₄ are the same, or different, and each ishydrogen or an acyl radical of

a. an unbranched fatty acid with 5 to 22 carbon atoms,

b. an amino acid selected from the group consisting of glycine, the Lforms of phenylalanine, alanine, valine, leucine, isoleucine, tyrosine,proline, hydroxyproline, serine, threonine, cystine, cysteine, asparticacid, glutamic acid, arginine, lysine, histidine carnitine andornithine,

c. a dicarboxylic acid having 3-22 carbon atoms,

d. a carboxylic acid selected from one or more of the group consistingof glycolic acid, pyruvic acid, lactic acid, enolpyruvic acid, lipoicacid, pantothenic acid, acetoacetic acid, p-aminobenzoic acid,betahydroxybutyric acid, orotic acid, and creatine.

(5) An acyl derivative of uridine having the formula: ##STR13## whereinat least one of R₁, R₂, or R₃ is a hydrocarbyloxycarbonyl moietycontaining 2-26 carbon atoms and the remaining R substituents areindependently a hydrocarbyloxycarbonyl or hydrocarbylcarbonyl moiety orH or phosphate.

(6) An acyl derivative of cytidine having the formula: ##STR14## whereinat least one of R₁, R₂, R₃ or R₄ is a hydrocarbyloxycarbonyl moietycontaining 2-26 carbon atoms and the remaining R substituents areindependently a hydrocarbyloxycarbonyl or hydrocarbylcarbonyl moiety orH or phosphate.

(7) Orotic acid or salts thereof: ##STR15##

Pharmaceutically-acceptable salts of orotic acid include those in whichthe cationic component of the salt is sodium, potassium, a basic aminoacid such as arginine or lysine, methylglucamine, choline, or any othersubstantially nontoxic water soluble cation with a molecular weight lessthan about daltons.

8) Alcohol-substituted orotate derivatives: ##STR16## wherein R₁ is aradical of an alcohol containing 1 to 20 carbon atoms joined to orotatevia an ester linkage.

Also encompassed by the invention are the pharmaceutically acceptablesalts of the above-noted compounds.

Advantageous compounds of the invention are short-chain (2 to 6 carbonatoms) fatty acid esters of uridine or cytidine. Particularlyadvantageous compounds are triacetyluridine or triacetylcytidine.

Inhibitors of Uridine Phosphorylase

Examples of inhibitors of uridine phosphorylase include but are notlimited to 5-benzyl barbiturate or 5-benzylidene barbiturate derivativesincluding 5-benzyl barbiturate, 5-benzyloxybenzyl barbiturate,5-benzyloxybenzyl-1- (1-hydroxy-2-ethoxy)methyl! barbiturate,5-benzyloxybenzylacetyl-1- (1-hydroxy-2-ethoxy)methyl! barbiturate, and5-methoxybenzylacetylacyclobarbiturate, 2,2'-anhydro-5-ethyluridine,5-ethyl-2-deoxyuridine and acyclouridine compounds, particularly5-benzyl substituted acyclouridine congeners including but not limitedto benzylacyclouridine, benzyloxybenzylacyclouridine,aminomethyl-benzylacyclouridine,aminomethylbenzyloxybenzylacyclouridine,hydroxymethyl-benzylacyclouridine, andhydroxymethyl-benzyloxybenzylacyclouridine. See also WO 89/09603 and WO91/16315, hereby incorporated by reference.

Compositions of the Invention

In one embodiment of the invention, novel pharmaceutical compositionscomprise as an active agent one or more pyrimidine nucleotide precursorsselected from the group comprised of uridine, cytidine or orotic acid orits salts, and acyl derivatives of these pyrimidine nucleotideprecursors, together with a pharmaceutically acceptable carrier.

The compositions, depending on the intended use and route ofadministration, are manufactured in the form of a liquid, a suspension,a tablet, a capsule, a dragee, an injectable solution, or a suppository(see discussion of formulation below).

In another embodiment of the invention, the composition comprises atleast one pyrimidine nucleotide precursor and an agent which inhibitsthe degradation of uridine, such as an inhibitor of the enzyme uridinephosphorylase. Examples of inhibitors of uridine phosphorylase includebut are not limited to 5-benzyl barbiturate or 5-benzylidene barbituratederivatives including 5-benzyl barbiturate, 5-benzyloxybenzylbarbiturate, 5-benzyloxybenzyl-1- (1-hydroxy-2-ethoxy)methyl!barbiturate, 5-benzyloxybenzylacetyl-1- (1-hydroxy-2-ethoxy)methyl!barbiturate, and 5-methoxybenzylacetylacyclobarbiturate,2,2'-anhydro-5-ethyluridine, and acyclouridine compounds, particularly5-benzyl substituted acyclouridine congeners including but not limitedto benzylacyclouridine, benzyloxybenzylacyclouridine,aminomethyl-benzylacyclouridine,aminomethylbenzyloxybenzylacyclouridine,hydroxymethyl-benzylacyclouridine, andhydroxymethyl-benzyloxybenzylacyclouridine. See also U.S. Pat. No.5,077,280 and WO 91/16315, hereby incorporated by reference.Furthermore, it is within the scope of the invention to utilize aninhibitor of uridine phosphorylase alone, without coadministration of apyrimidine nucleotide precursor, for the purpose of improving tissueresistance to endotoxin or inflammatory mediators.

In another embodiment, the compounds of the invention include inaddition to one or more compounds of the invention, and at least one ofthe following compounds which are also useful for treating endotoxintoxicity or sepsis: Antibodies or other proteins which bind toendotoxin, TNF or IL-1; Polymyxin B conjugated to a polymeric supportmatrix (in order to reduce Polymyxin B toxicity while taking advantageof its capacity to bind and inactivate endotoxin); antagonists of IL-1or TNF receptors; antibiotics; inhibitors of the arachidonic acidcascade; arginine or ornithine; corticosteroids; glucose; ATP; purinenucleotide precursors including inosine, adenosine, or acyl derivativesthereof; cyclic AMP or acyl derivatives thereof.

In another embodiment of the invention, the composition comprises atleast one compound of the invention and an antibacterial, antifungal, orantiviral compound.

Therapeutic Uses of the Compounds and Compositions of the Invention

The compounds, compositions, and methods of the invention are useful toenhance resistance to endotoxin or other inflammatory stimuli ormediators in animals. The compounds include pyrimidine nucleotideprecursors as well as compounds which inhibit enzymatic degradation ofuridine.

The compounds and compositions of the invention are useful in treatingmammals including humans; however, the invention is not intended to beso limited, it being within the contemplation of the invention to treatall animals that experience a beneficial effect from the administrationof the active compounds of the invention.

A primary feature of the invention is the discovery that administrationof uridine nucleotide precursors results in supra-normal resistance totoxic or lethal effects of endotoxin or other inflammatory stimuli ormediators in vivo.

The invention is furthermore embodied in the oral or systemicadministration of a pharmaceutical compound or composition containingpyrimidine nucleotide precursors and/or agents which inhibit uridinecatabolism, for the purpose of enhancing resistance to endotoxin, otherinflammatory stimuli, or their mediators.

SIRS, Sepsis and Septic Shock

The compounds, compositions, and methods of the invention are useful forreducing tissue damage due to systemic inflammatory response syndrome(SIRS), including sepsis, triggered by bacterial (both gram-positive andgram-negative), viral, fungal, or parasitic (e.g. malaria) organisms.All of these types of infective organisms stimulate the formation orrelease of endogenous inflammatory mediators, resulting in tissuedamage.

The compounds and compositions of the invention are administered topatients with symptoms of sepsis, e.g. fever, neutropenia, hypotension,etc., or prophylactically to patients at risk for sepsis, e.g. surgicalpatients, patients with serious burns or wounds, or patients withurinary tract catheters.

The compounds of the invention are optionally administered inconjunction with other agents which are useful in treating sepsis,including but not limited to one or more of the following: Antibodies orother proteins which bind to endotoxin, TNF or IL-1; Polymyxin Bconjugated to a polymeric support matrix (in order to reduce Polymyxin Btoxicity while taking advantage of its capacity to bind and inactivateendotoxin); antagonists of IL-1 or TNF receptors; antibiotics;inhibitors of the arachidonic acid cascade; leukotriene antagonists;arginine or ornithine; corticosteroids; glucose; ATP; inosine; cyclicAMP or acyl derivatives thereof. The compounds of the invention areadministered either before, after, or during exposure of the animal orpatient to one or more of these other agents.

For treatment or prevention of tissue damage due to sepsis, doses of thecompounds of the invention ranging from about 0.5 to about 40 grams perday, advantageously 3 to 30 grams per day, are administered, dependingon the therapeutic response and the condition of the patient. Inpatients with serious sepsis syndrome, the compounds of the inventionare typically administered in liquid or suspension form via anasogastric tube, especially if such a tube is already in place fordelivery of nutrient suspensions or other enteraI nutrition products.Patients with less serious illness typically receive compounds of theinvention in either liquid form, or in capsules or tablets. Patients whodo not tolerate oral administration of the compounds and compositions ofthe invention (e.g. patients on total parenteral nutrition due togastrointestinal tract damage) receive compounds of the invention thatare sufficiently water soluble, such as uridine itself, by intravenousinfusion.

Following an episode of shock, trauma or sepsis, patients often enterinto a persistent state of hypermetabolism which can lead to multipleorgan failure, usually beginning with hepatic failure. Thehypermetabolic phase is due to the influence of endotoxin and itsmediators on metabolic regulation (Cerra et al., in Molecular andCellular Mechanisms of Septic Shock, 265-277, Alan R. Liss, 1989).Hypermetabolism-organ failure is one of the leading causes of mortalityamong surgical intensive care patients. As demonstrated in the Examples,the compounds, compositions and methods of the invention are effectivein reducing tissue damage and improving survival in animals subjected toendotoxin or other inducers of sepsis and organ failure. The compounds,compositions, and methods of the invention are useful in the treatmentof patients at risk for hypermetabolic organ failure.

A serious consequence of sepsis is a propensity toward coagulationdisorders, especially disseminated intravascular coagulation (DIC). InDIC, both blood coagulation and fibrinolysis are activated, so thatblood clotting factors are rapidly consumed and aggregates of thrombinform in the circulation. DIC can result in either (or both) hemorrhageor thrombus formation. The liver is the primary site for synthesis ofclotting factors and for clearing micro-aggregates of thrombin from thecirculation. The protective and therapeutic effects of the compounds,compositions, and methods of the invention attenuate sepsis-inducedalterations in blood coagulation (see Example 11).

Reduction of Toxicity of Therapeutic Cytokines

Many of the biological effects of endotoxin and other inflammatorystimuli are mediated by the release of endogenous bioactive molecules(mediators) from target cells, particularly macrophages and Kupffercells (sessile macrophages in the liver). Evidence for this is thatmacrophages in the C3H/HEJ strain of mice are genetically non-responsiveto endotoxin (in terms of releasing cytokines upon exposure toendotoxin), and endotoxin is relatively non-toxic in this strain. Thesemice are however sensitive to bioactive peptides normally released frommacrophages, e.g. tumor necrosis factor (TNF), and toxicity of LPS isrestored by transplantation of normal macrophages. TNF is generally heldto be a primary mediator of endotoxin toxicity, but interleukin-1 (IL-1)and other agents also participate in the expression of endotoxintoxicity and sepsis.

Compounds, compositions, and methods of the invention are thus useful inmodifying biological effects of inflammatory cytokines, whether producedendogenously (especially from macrophages), or introduced into the bodyfrom exogenous sources (e.g. polypeptides produced by recombinant DNAand fermentation technology).

Various inflammatory cytokines and even endotoxin itself have potentialtherapeutic applications. Tumor necrosis factor, as suggested by itsname, can destroy tumors and synergizes with interferon-alpha ininhibiting viral infections. Thus, TNF, and even bacterial endotoxinitself (which elicits the release of endogenous TNF), have beenadministered to patients for the treatment of cancer. Classes ofinflammatory cytokines with both therapeutic activity and toxicity whichlimits their clinical use include TNF, interleukins and interferons. Thecompounds, compositions and methods of the invention are useful inpreventing or treating toxicity which occurs during therapeuticadministration of such cytokines as well as inflammatory stimuli.

When endotoxin is administered to cancer patients by intravenousinfusion, hepatic toxicity limits the dose of endotoxin which can beadministered (Engelhardt R et al., Cancer. Res. 1991 51:2524-30). Innon-hepatic cancers, protection of the liver from endotoxin permitsadministration of higher doses of endotoxin in order to maximize itsantitumor efficacy. Endotoxin also has immunostimulant properties. Thecompounds of the invention are thus useful for improving the therapeuticindex of endotoxin, endotoxin analogs or derivatives (e.g. Lipid A,Lipid X, Monophosphoryl Lipid A, etc.) or their mediators. Hepatictoxicity is also dose-limiting during intentional administration of TNFto humans (Kimura et al., Cancer Chemother. Pharmacol. 1987,20:223-229). Inflammatory stimuli of yeast or fungal origin, such as thepolysaccharides glucan or lentinan are also used therapeutically asimmunomodulators for treatment of infections or cancer (Seljelid, Scand.J. Immunol. 1989, 29:181-92; Bowers et al., J. Surg. Res.1989;47:183-8). Double-stranded RNA, such polyinosine-polycytidine, alsohas therapeutic activity as an inflammatory stimulus for treatment ofcancer or infections.

The inflammatory peptide Interleukin-1 (IL-1), which mediates someactions of endotoxin, similarly has important therapeutic potential(e.g. in restoring hematopoiesis after damage caused by cancerchemotherapy), but its use is limited by toxic side effects which may beattenuated by utilization of the compounds, compositions, and methods ofthe invention.

Interleukin-2 (IL-2) is used clinically for treatment of severalvarieties of cancer; it also has potential activity as animmunomodulator in treatment of various infections and in modulating theresponse to vaccines. Hepatic toxicity in response to IL-2 is notuncommon in patients receiving therapeutic doses of IL-2 for cancertreatment (Viens et al., J. Immunother. 1992 11:218-24). In anexperimental model of autoimmune hepatitis induced by administration ofconcanavalin A to mice, hepatic damage is reported to be related toelevated production of endogenous IL-2 (Tiegs et al., J. Clin. Invest.1992 90:196-203); as demonstrated in Example 10, compounds,compositions, and methods of the invention are effective in attenuatinghepatic damage in this model. The compounds, compositions, and methodsof the invention are useful in reducing side effects when administeredin conjunction with IL-2; furthermore, the compounds, compositions, andmethods of the inventions are useful in treating autoimmune hepatitis.

Interleukin 6, which has therapeutic potential in improving bloodplatelet production, induces hepatic TNF receptors, thus increasingtissue sensitivity to TNF. The compounds, compositions, and methods ofthe invention are thus useful for use in combination with IL-6 orsimilar agents which affect tissue senstivity to, or production of, TNF(Van Bladel et al., Cytokine, 1991 3:149-54).

The combination of a particular therapeutic cytokine and a pyrimidinenucleotide precursor and/or a uridine phosphorylase inhibitor is usedfor treatment of the disorders for which the particular therapeuticcytokine is known to be effective. For example, interleukin 2 is usedfor treatment of renal cancer, colon cancer, melanoma, lymphoma,leukemia and other neoplastic conditions. TNF has antitumor efficacyagainst a variety of cancer types, but its use in therapy has heretoforebeen limited by its toxicity, (Kimura et al., Cancer. Chemother.Pharmacol. 1987; 20:223-9). Endotoxin has shown significant antitumorefficacy (Engelhardt R et al., Cancer. Res. 1991 51:2524-30).

For prevention or treatment of toxicity due to administration oftherapeutic cytokines, approximately 0.5 to 40 grams of a pyrimidinenucleotide precursor is administered daily for one to several days,depending on the duration of the cytokine treatment. The pyrimidinenucleotide precursors are administered before, during, or afteradministration of the therapeutic cytokine. The therapeutic cytokinesare administered in the particular doses and regimens alreadyestablished for experimental and clinical treatment of various forms ofcancer, except that increased doses of cytokines may be tolerated whenthe pyrimidine nucleotide precursors of the invention are administered,as would be determined in simple dose-escalation studies for eachcytokine or inflammatory stimulus.

Inflammatory Hepatitis: Liver Disorders Involving Endotoxin or Mediators

The liver is susceptible to damage by endotoxin or its mediators,particularly when liver function is impaired. Liver damage from manyoriginating causes (e.g. choline deficiency, Reye's syndrome, oralcohol) which either increase hepatic sensitivity to endotoxin orinhibit endotoxin clearance, is in part mediated by bacterial endotoxin(normally present in the portal circulation due to leakage of smallamounts from the intestine into the bloodstream) or mediators elicitedby endotoxin (Nolan, Gastroenterology, 1975 69:1346-1356; Nolan,Hepatology 1989 10:887-91). Hepatic toxicity is dose-limiting inpatients receiving intentional injections of endotoxin for possibleefficacy in treating cancer (Engelhardt et al., Cancer Research, 199151:2524-2530).

As is demonstrated in the Examples below, the compounds, compositions,and methods of the invention significantly reduce hepatic damage inducedby endotoxin and other inflammatory stimuli and mediators. Thecompounds, compositions, and methods of the invention are useful intreating, preventing, or attenuating liver damage in a large variety ofconditions in which hepatoxicity due to endotoxin or othe inflammatorystimuli or mediators are implicated in their etiology (whether or notsystemic sepsis syndrome is present). Conditions in which damage to theliver by endotoxin or its mediators (e.g. TNF) are implicated includebut are not limited to the following disease states:

A. Reye's syndrome

Reye's syndrome is characterized by rapid hepatic failure and is mostcommonly found in children as a complication of influenza and otherviral infections; aspirin may be a risk factor. The etiology of Reye'ssyndrome is believed to involve endotoxin or inflammatory mediators.Endotoxemia is found in most or all patients with Reye's syndrome; ananimal model for Reye's syndrome involves treating rats with acombination of endotoxin and aspirin (Kilpatrick et al., Metabolism,1989, 38:73-7).

B. Alcoholic Liver Damage

Excessive consumption of ethanol, in addition to problems associatedwith impaired mental and physical control associated with ethanolintoxication, is a significant cause of liver injury in humans.Endotoxin and TNF contribute to hepatic problems associated withexposure to alcohol. (Nolan J P, Hepatology 1989 10:887-91; Arai M,Nakano S, Okuno F, et al. Hepatology 1989; 9:846-851; McClain C J andCohen D A, Hepatotogy 1989; 9:349-351).

C. Fulminant Hepatitis

Tumor necrosis factor is implicated in the etiology and progression offulminant hepatitis, which can rapidly lead to hepatic failure and death(Aderka et al., Med Hypotheses, 1988 27:193-6)

D. Viral Hepatitis

Endotoxin contributes to hepatocyte damage occurring during viralhepatitis. Viral hepatitis reduces the LD₅₀ of endotoxin in animalmodels, and exclusion of endogenous endotoxin from experimental animals(by colectomy or by using axenic rodents) reduces the hepatic damagecaused by a viral challenge. (Gut et al., J. Infect. Disease., 1984,149:621). In some cases of hepatitis, immune or inflammatory responsesto hepatic viral infection mediated by T lymphocytes or macrophagescontributes to liver damage. In either situation, the compounds,compositions, and methods of the invention are useful for treatinghepatic damage related to viral infection. Example 14 demonstrates thatthe compounds and methods of the invention improve survival in an animalmodel of viral hepatitis.

Immunopathology contributes to liver injury in viral hepatitis inhumans. Hepatitis B and C viruses do not necessarily directly injurecells. There is substantial evidence that immune responses to infectedcells contributes significantly to liver injury. Activated cytotoxic Tlymphocytes attack antigen-bearing infected cells, but also releasecytokines like interferon-gamma which then recruit and activateinflammatory leukocytes in the liver and enhance hepatic sensitivity tomacrophage activators like endotoxin (Ando et al., J. Exp Med.178:1541-1554, 1993). In Examples 10 and 12, beneficial effects ofcompounds, compositions, and methods of the invention are presented inexperimental models mimicking the key features of T Cell-mediatedhepatic inflammatory injury with and without secondary exacerbationcaused by endotoxin. These Examples support the utility of thecompounds, compositions, and methods of the invention in viralhepatitis, as well as in autoimmune hepatitis and cell-mediated livergraft rejection.

E. Parasitic Infections

Hepatic damage and morbidity which occurs during malaria infection ismediated in part by TNF (Clark et al., Am. J. Pathol. 1987, 129:192-9).

F. Hepatic Damage During Total Parenteral Nutrition

Hepatic complications are common in patients receiving total parentalnutrition (TPN) and who have no underlying liver disease; exacerbationof pre-existing liver injury also occurs during TPN. Pappo et al. (J.Surg. Res., 1991, 51:106-12) reported that endotoxin (LPS) derived fromthe overgrowth of intestinal gram-negative bacteria is responsible forTPN-associated hepatic steatosis, and that bowel decontamination andspecific anti-LPS activity of polymyxin B will reduce fatty infiltrationof the liver during TPN. Polymyxin B, which binds to and inactivatesLPS, is toxic in humans, but served to demonstrate that hepatopathyobserved during TPN is in fact mediated in part by endotoxin or TNF.Therefore, inclusion of effective amounts of compounds of the inventionin TPN solutions is useful for reducing TPN-induced liver damage, aswell as for treating underlying inflammatory liver injury. Compounds ofthe invention, especially uridine, cytidine, orotic acid, or watersoluble salts and esters thereof, are either included in a TPNformulation or are administered separately but concurrently with TPNinfusion. A typical TPN formula contains the basic nutrients needed tofulfill nutritional requirements in a form that is acceptable forintravenous administration. Thus, macromolecular dietary constituentslike proteins or starches are provided in partially or fully digestedform, e.g. as amino acids or sugars. A typical TPN formulation containsnot only amino acids and sugars, but also other required nutrients likevitamins, minerals, and fats. Preferred doses of compounds of theinvention to be used in conjunction with, or as constituents of, TPNformulas are in the range of 1 to 40 grams per day (usually in the rangeof 2 to 20 grams per day) either as a bolus injection or as a sustainedinfusion.

In the context of this embodiment of the invention, a patient need notbe receiving all of his or her nutrient requirements by the parenteralroute in order to obtain benefit from the compounds, compositions, andmethods of the invention. However, this embodiment of the invention isparticularly advantageous where patients are receiving 50% or more oftheir nutrient requirements by intravenous infusion.

Lead Poisoning

Lead poisoning can dramatically increase sensitivity to endotoxin.Lead-induced interference with hepatic metabolism is implicated in theeffect of lead on endotoxin toxicity (Taki et al., Eur. Surg. Res.,1985, 17:140-9).

Partial Hepatectomy

Following partial hepatectomy (e.g. for removal of cancerous tissue),morbidity and mortality from hepatic failure is not uncommon. Livertissue undergoing regeneration after partial hepatectomy in animals ishypersensitive to the deleterious effects of endotoxin and mediators(Shirai et al., Acta Pathol. Jpn., 1987, 37:1127-1134).

I. Postanesthetic Hepatitis

Inhalation anesthetics such as halothane can induce hepatitis,particularly if hepatic bloodflow is also impaired. Endotoxin isimplicated in the etiology of postanesthetic hepatitis (Lomanto et al.,Anesth. Analg., 1972, 51:264-270); the compounds of the invention arethus useful for administration to patients (prophylactically,therapeutically, or both) undergoing inhalation anesthesia forpreventing and treating hepatitis. Trauma itself may contribute topostanesthetic hepatitis. Trauma furthermore often induces translocationof bacteria and endotoxin from the gut into other tissues via thebloodstream. Surgery patients are among the groups most susceptible toendotoxin poisoning (due to infection). Therefore, treatment of surgicalpatients with pyrimidine nucleotide precursors (before, during, or aftersurgery) significantly improves their resistance to endotoxin poisoning.J. Cholestatic Hepatitis

Hepatic injury due to bile duct obstruction or intrahepatic cholestasisis in part due to enterally-derived endotoxin. (Shibayama Y, 1989, J.Pathol. 159:335-9).

K. Liver Transplantation

In patients receiving liver transplants, the presence of high levels ofendotoxin or inflammatory mediators preoperatively and at the end of theanhepatic period is associated with graft failure and a high mortality.Patients with primary nonfunction of their transplants typically havesevere endotoxemia. Endotoxemia is implicated as a cause rather than aneffect of perioperative complications and graft loss (Yokoyama et al,1989, Transplant Proc. 21:3833-41). In a clinical situation, an animal,such as a human, receives a compound of the invention enterally orparenterally after a transplant, in doses ranging from about 1 to about40 grams per day, though typically 2 to 20 grams, advantageously dividedinto one to about four doses or else administered as a continuous orintermittent enteral or parenteral infusion. A compound of the inventionis also optionally incorporated into an enteral or parenteral nutritionformulation prior to administration. Patients often receive intravenousisotonic (5%) glucose for several days after liver transplantation as analternative to more complete parenteral or enteral nutrition. A compoundof the invention, especially uridine or cytidine, is advantageouslyformulated in an aqueous solution of 1 to 10% glucose. In a preferredembodiment, 1 to 40 grams per day, advantageously 2 to 20 grams, of apyrimidine nucleotide precursor are administered per day. A secondarybenefit of pyrimidine nucleotide precursors in liver disease or inrecovery from a transplant is improved peripheral glucose utilization.

The donor liver can also be perfused with a solution containing acompound of the invention, advantageously uridine, cytidine, orotic acidor salts or acyl derivatives thereof, prior to or during implantation inthe recipient. A pyrimidine nucleotide precursor, especially uridine, isincluded in a liver perfusion solution (also containing appropriate ionsand other metabolites like glucose) at concentrations ranging from 10micromolar to 10 millimolar.

Endotoxins and inflammatory mediators are also involved in other hepaticdisorders; the diversity of the specific examples discussed above serveto indicate that the compounds, compositions, and methods of theinvention are useful in treating or preventing a broad variety of liverdiseases.

For treatment of inflammatory hepatitis, 0.5 to 40 grams (advantageously3 to 30 grams) of a pyrimidine nucleotide precursor are administereddaily, advantageously divided into one to about four doses. The durationof the treatment regimen depends on improvement of clinical symptoms;acute inflammatory liver disorders will typically require a shortercourse of treatment than chronic degenerative conditions.

Other Disorders

As is demonstrated in Examples 2, 4-6, and 9, the compounds of theinvention protect tissues other than liver, e.g. muscle, as indicated byserum creatine phosphokinase (CPK) levels in animals treated withendotoxin or the fungal inflammatory agent zymosan. Serum CPK activityis elevated as a consequence of damage to skeletal or heart muscle.

Cachexia, a syndrome of weight loss, tissue wasting and misutilizationof nutrients is a common complication in patients with cancer. TNF andother inflammatory cytokines are implicated in the initiation andmaintenance of cachectic states; "Cachectin" is a synonym for TNF. Thecompounds, compositions, and methods of the invention are useful fortreating patients with cachexia.

Clearance of ethanol from the circulation is a process that is largelydependent on energy metabolism and redox balance in the liver, inaddition to levels of the enzyme alcohol dehydrogenase. Example 13demonstrates that compounds of the invention improve recovery fromsevere ethanol intoxication. The compounds and compositions of theinvention are useful in reducing the severity of both the mental andphysical impairment due to alcohol intoxication as well as longer-termhealth consequences of chronic alcohol ingestion such as liver injury.Compounds of the invention (e.g. triacetyluridine, uridine or cytidine)are administered orally before, during, or after ingestion of ethanol indoses of 0.5 to 40 grams per day, advantageously 1 to 20 grams.

Veterinary Applications

In horses and other large animals, there is a common syndrome known aslaminitis, which is one consequence of endotoxin from the gut enteringinto the systemic circulation (often after the animal overeatscarbohydrate-rich foods, changing the bacterial populations in the gut).The compounds, compositions, and methods of the invention, since theyattenuate tissue damage due to endotoxin, are useful in treating orpreventing laminitis and other effects of endotoxin poisoning inanimals.

Administration and Formulation of Compounds and Compositions of theInvention

The compounds and compositions of the invention are administered orally,by parenteral injection, intravenously, or by other means, depending onthe condition being treated and the status of the patient.

The compounds and compositions of the invention are administeredchronically, intermittently, or acutely as needed. In the case of anevent which involves endotoxin toxicity or systemic inflammatorysyndrome, the compounds and compositions are administered prior to,during, or after such event.

The pharmacologically active compounds optionally are combined withsuitable pharmaceutically acceptable carriers comprising excipients andauxiliaries which facilitate processing of the active compounds. Theseare administered as tablets, dragees, capsules, and suppositories. Thecompositions are administered for example orally, rectally, vaginally,or released through the buccal pouch of the mouth, and may be applied insolution form by injection, orally or by topical administration. Thecompositions may contain from about 0.1 to 99 percent, preferably fromabout 50 to 90 percent of the active compound(s), together with theexcipient(s).

For parenteral administration by injection or intravenous infusion, theactive compounds are suspended or dissolved in aqueous medium such assterile water or saline solution. Injectable solutions or suspensionsoptionally contain a surfactant agent such as polyoxyethylenesorbitanesters, sorbitan esters, polyoxyethylene ethers, or solubilizing agentslike propylene glycol or ethanol. The solution typically contains 1 to25% of the active compounds. In one embodiment of the invention, theaqueous medium is a solution of 1 to 10% glucose in water or isotonicsaline. In some circumstances concurrent intravenous adminisration ofglucose and a compound of the invention, especially uridine, isadvantageous. Uridine (and acyl derivatives of uridine) improve glucoseperipheral glucose utilization, and insulin (which is generally releasedfrom the pancreas in response Go glucose or other carbohydrates or someamino acids) enhances nucleoside uptake and utilization by cells.

For use in conjunction with parenteral nutrition, compounds of theinvention are dissolved or suspended in parenteral nutrition products,either during manufacture of such products or shortly prior to theiradministration to patients. The concentration of pyridimine nucleotideprecursor is adjusted in the parenteral nutrition formulation so that 1to 40 grams, generally 2 to 20 grams, are delivered per day duringinfusion of the parenteral nutrition product. A typically parenteralnutrition formula contains and delivers nutritionally adequate portionsof amino acids, carbohydrates, fats, vitamins, and minerals in sterilecompositions suitable for intreavenous adminstration.

Suitable excipients include fillers such as sugars, for example lactose,sucrose, mannitol or sorbitol, cellulose preparations and/or calciumphosphates, for example tricalcium phosphate or calcium hydrogenphosphate, as well as binders such as starch paste using, for example,maize starch, wheat starch, rice starch or potato starch, gelatin,tragacanth, methyl cellu-lose, hydroxypropylmethyl cellulose, sodiumcarboxymethyl cellulose and/or polyvinyl pyrrolidone.

Auxiliaries include flow-regulating agents and lubricants, for example,silica, talc, stearic acid or salts thereof, such as magnesium stearateor calcium stearate and/or polyethylene glycol. Dragee cores areprovided with suitable coatings which, if desired, are resistant togastric juices. For this purpose, concentrated sugar solutions are used,which optionally contain gum arabic, talc, polyvinyl pyrrolidone,polyethylene glycol and/or titanium dioxide, lacquer solutions andsuitable organic solvents or solvent mixtures. In order to producecoatings resistant to gastric juices, solutions of suitable cellulosepreparations such as acetylcellulose phthalate orhydroxypropylmethylcellulose phthalate are used. Dyestuffs or pigmentsare optionally added to the tablets or dragee coatings, for example, foridentification or in order to characterize different compound doses.

The pharmaceutical preparations of the present invention aremanufactured in a manner which is itself known, for example, by means ofconventional mixing, granulating, dragee-making, dissolving, orlyophilizing processes. Thus, pharmaceutical preparations for oral useare obtained by combining the active compound(s) with solid excipients,optionally grinding the resulting mixture and processing the mixture ofgranules, after adding suitable auxiliaries, if desired or necessary, toobtain tablets or dragee cores.

Other pharmaceutical preparations which are useful for oral deliveryinclude push-fit capsules made of gelatin, as well as soft-sealedcapsules made of gelatin and a plasticizer such as glycerol or sorbitol.The push-fit capsules contain the active compound(s) in the form ofgranules which optionally are mixed with fillers such as lactose,binders such as starches and/or lubricants such as talc or magnesiumstearate, and, optionally stabilizers. In soft capsules, the activecompounds are preferably dissolved or suspended in suitable liquids suchas fatty oils, liquid paraffin, or polyethylene glycols. In addition,stabilizers optionally are added. Other formulations for oraladministration include solutions, suspensions, or emulsions. Inparticular, a liquid form suitable for administration via an enteralcatheter, e.g. a nasogastric tube, is advantageous, particularly forbedridden or unconscious patients.

Pharmaceutical preparations which are used rectally include, forexample, suppositories which consist of a combination of activecompounds with a suppository base. Suitable suppository bases are, forexample, natural or synthetic triglycerides, paraffin hydrocarbons,polyethylene glycols or higher alkanols. In addition, gelatin rectalcapsules which consist of a combination of the active compounds with abase are useful. Base materials include, for example, liquidtriglycerides, polyethylene glycols, or paraffin hydrocarbons.

Suitable formulations for parenteral administration include aqueoussolutions of the active compounds in water soluble form, for example,water soluble salts. In addition, suspensions of the active compounds asappropriate in oily injection suspensions are administered. Suitablelipophilic solvents or vehicles include fatty oils, for example, sesameoil, or synthetic fatty acid esters, for example, ethyl oleate ortri-glycerides. Aqueous injection suspensions optionally includesubstances which increase the viscosity of the suspension which include,for example, sodium carboxymethylcellulose, sorbitol and/or dextran. Thesuspension optionally contains stabilizers.

Synthesis of the Compounds of the Invention

Acylated derivatives of pyrimidine nucleosides are synthesized byreacting a pyrimidine nucleoside or congener with an activatedcarboxylic acid. An activated carboxylic acid is one that has beentreated with appropriate reagents to render its carboxylate carbon moresusceptible to nucleophilic attack than is the case in the originalcarboxylic acid. Examples of useful activated carboxylic acids forsynthesis of the compounds of the invention are acid chlorides, acidanhydrides, n-hydroxysuccinimide esters, or carboxylic acids activatedwith BOP-DC. Carboxylic acids may also be linked to pyrimidinenucleosides or congeners with coupling reagents likedicyclohexylcarbodiimide (DCC).

During preparation of the acyl compounds of the invention, when the acidsource of the desired acyl derivative has groups which interfere withthe acylation reactions, e.g., hydroxyl or amino groups, these groupsare blocked with protecting groups, e.g., t-butyldimethylsilyl ethers ort-BOC groups, respectively, before preparation of the anhydride. Forexample, lactic acid is converted to 2-t-butyldimethylsiloxypropionicacid with t-butyldimethylchlorosilane, followed by hydrolysis of theresulting silyl ester with aqueous base. The anhydride is formed byreacting the protected acid with DCC. With amino acids, the N-t-BOCderivative is prepared, using standard techniques, which is thenconverted to the anhydride with DCC. With acids containing more than onecarboxylate group (e.g., succinic, fumaric, or adipic acid) the acidanhydride of the desired dicarboxylic acid is reacted with a pyrimidinenucleoside in pyridine or pyridine plus dimethylformamide ordimethylacetamide.

Amino acids are coupled to the exocyclic amino groups of cytidine, andto hydroxyl groups on the aldose moiety of pyrimidine nucleosides ortheir congeners, by standard methods using DCC in a suitable solvent,particularly a mixture of (i) methylene chloride and (ii)dimethylacetamide or dimethylformamide.

Carbyloxycarbonyl derivatives of non-methylated pyrimidine nucleosidesare prepared by reacting the nucleoside with the appropriatecarbylchloroformate in a solvent such as pyridine or pyridine plusdimethylformamide under anhydrous conditions. The solvent is removedunder vacuum, and the residue is purified by column chromatography.

It will be obvious to the person skilled in the art that other methodsof synthesis can be used to prepare the compounds of the invention.

The following examples are illustrative, but not limiting of the methodsand compositions of the present invention. Other suitable modificationsand adaptations of a variety of conditions and parameters normallyencountered in clinical therapy which are obvious to those skilled inthe art are within the spirit and scope of this invention.

EXAMPLES Example 1 Triacetyluridine and Uridine Improve Survival in MiceTreated with Killed E. coli

Purpose:

Sepsis syndrome can be initiated by gram-negative bacteria even if theyare not alive, since the primary trigger is endotoxin, a component ofthe bacterial cell wall. The purpose of this study was to determine theeffect of oral triacetyluridine and parenteral uridine on survival ofmice treated with a lethal dose of killed E. coli bacteria.

Methods:

Eighteen female Balb/C mice (eight weeks old) were divided into groupsof six animals each. All mice received 500 micrograms of an acetonepowder of E. coli (serotype 0111:B4) suspended by sonication in 0.2 mlof saline. Mice in one group received uridine (2000 mg/kg in 0.2 mlsaline) by i.p. injection two hours prior to administration of the E.Coli. Another group of mice received triacetyluridine (6000 mg/kg in avehicle of 1:1 corn oil/water containing 2.5% Tween 80) by oralintubation. Survival was monitored for one week.

A. n=6 E. coli (Control)

B. n=6 E. coli (Control)+Urd i.p.

C. n=6 E. coli (Control)+TAU p.o.

Results:

Animals in the Control group appeared to be in shock and werehypothermic 18 hours after administration of the E. coli powder. Animalsin the treated groups were active and maintaining body temperature,although their coats were scruffy throughout the first 48 hours of theobservation period. Animals surviving 48 hours recovered completely. Allof the mice treated only with E. coli died within 48 hours. All micetreated with either uridine or triacetyluridine survived administrationof killed E. coli.

Example 2 Dose-response Study of Uridine in Protection of Tissues FromEndotoxin Damage

Purpose:

The purpose of this study was to determine the dose-responsecharacteristics for uridine in prevention of inflammatory tissue damagecaused by endotoxin (LPS).

Methods:

Female Balb/C mice (eight weeks old) were divided into six groups of sixanimals each. One group of animals remained untreated to provide basalvalues for serum chemistry indices of tissue damage. Mice in theremaining five groups received 100 micrograms of Salmonella typhimuriumendotoxin by i.p. injection in a volume 0.2 ml saline. Two hours priorto endotoxin administration, the five groups of mice received uridine indoses of 0, 500, 1000, 2000 and 4000 mg/kg i.p. (in 0.2 ml saline)respectively. Eighteen hours after endotoxin administration, bloodsamples were collected for determination of serum chemistry values ofindicators of tissue damage.

Results:

Uridine produced a dose-dependent protection of tissues against damagefrom endotoxin administration. ALT, AST, and SDH are specific indicatorsof liver damage; CPK is an indicator of damage to muscle; LDH isreleased from both liver and muscle. The most effective uridine dose inmice in this experiment was 2000 mg/kg.

                                      TABLE 1                                     __________________________________________________________________________    Uridine attenuates endotoxin-induced tissue damage                                   ALT    AST    LDH    CPK     SDH                                       __________________________________________________________________________    Basal (No LPS)                                                                       198 ± 124                                                                         137 ± 26                                                                          708 ± 177                                                                         906 ± 211                                                                          49 ± 2                                 Control (LPS)                                                                        3768 ± 482                                                                        4176 ± 459                                                                        8406 ± 850                                                                        11628 ± 2398                                                                       1170 ± 157                             Uridine 500                                                                          2568 ± 678                                                                        3090 ± 871                                                                        5988 ± 1225                                                                       8832 ± 1089                                                                        834 ± 192                              Uridine 1000                                                                         1338 ± 401*                                                                        1206 ± 314*                                                                      3101 ± 860*                                                                       4431 ± 1529*                                                                       404 ± 95*                              Uridine 2000                                                                          605 ± 236*                                                                        620 ± 174*                                                                       1990 ± 642*                                                                       4531 ± 2139*                                                                       125 ± 45*                              Uridine 4000                                                                         1120 ± 970*                                                                        744 ± 457*                                                                        3441 ± 2378*                                                                     8680 ± 6746*                                                                       135 ± 75*                              __________________________________________________________________________     * = Different from Control (LPS i.p.), P < .02                                ALT = Alanine Aminotransferase                                                AST = Aspartate Aminotransferase                                              LDH = Lactate Dehydrogenase                                                   CPK = Creatine Phosphokinase                                                  SDH = Sorbitol Dehydrogenase                                             

Example 3 Oral Triacetyluridine Improves Survival of Mice Treated With ALethal Dose of Salmonella typhimurium Endotoxin

Purpose:

Sepsis syndrome caused by gram-negative bacteria is mediated primarilythrough endotoxin, a lipopolysaccharide constituent of the bacterialwall. The purpose of this experiment was to determine the effect of anorally-administered uridine prodrug (Triacetyluridine; TAU) on survivalof mice treated with a lethal dose of purified Salmonella typhimuriumendotoxin (LPS).

Methods:

Twenty female Balb/C mice (eight weeks old) were divided into two groupsof ten animals each. All mice received 100 micrograms of Salmonellatyphimurium endotoxin by intraperitoneal injection in 0.2 ml of saline.One group of mice received triacetyluridine (6000 mg/kg in a vehicle of1:1 corn oil/water containing 2.5 % Tween 80) by oral intubation.Survival was monitored for one week.

Results:

All ten of the animals which received endotoxin alone died within 48hours. Nine of the ten mice that received oral TAU survived for theseven day observation period and appeared to have recovered completely.

Example 4 Oral Triacetyluridine Reduces Tissue Damage Caused ByEndotoxin

Purpose:

Bacterial endotoxin causes damage to the liver and other organs whichcan be assessed and quantified by determining serum levels of enzymesand other markers of tissue integrity and function. The purpose of thisstudy was to determine the dose-response characteristics oforally-administered triacetyl uridine (TAU) in attenuating tissue damagedue to endotoxin.

Methods:

Female Balb/C mice (eight weeks old) were divided into groups of fiveanimals each. One group of animals remained untreated to provide basalvalues for serum chemistry indices of tissue damage. Mice in the otherfour groups received 100 micrograms of Salmonella typhimurium endotoxinby i.p. injection, in a volume 0.2 ml saline. Three groups ofendotoxin-treated mice also received TAU 2 hours before endotoxin indoses of 2000, 4000, and 6000 mg/kg by oral intubation in a volume of0.4 ml. The TAU was formulated as a suspension in 1%carboxymethylcellulose in water. The remaining group (Controls) receivedthe carboxymethylcellulose vehicle by oral intubation.

Results:

Oral TAU administration reduced the levels of serum chemistry indicatorsof tissue damage. The beneficial effect on prevention ofendotoxin-induced organ damage was dose dependent.

                  TABLE 2                                                         ______________________________________                                        TAU attenuates endotoxin-induced tissue damage                                        ALT     AST       LDH       SDH                                       ______________________________________                                        Basal (No LPS)                                                                          130 ± 46                                                                             148 ± 32                                                                             563 ± 132                                                                          41 ± 5                               Control (LPS)                                                                          3679 ± 703                                                                           4798 ± 927                                                                           6998 ± 1064                                                                        1128 ± 174                            TAU 2000 2632 ± 915                                                                           3151 ± 1085                                                                          5419 ± 1561                                                                         793 ± 294                            TAU 4000 1463 ± 382*                                                                          1940 ± 456*                                                                          3878 ± 672*                                                                         345 ± 106*                           TAU 6000  365 ± 91*                                                                            403 ± 61*                                                                           1221 ± 181*                                                                         104 ± 18*                            ______________________________________                                         * = Different from Control (LPS i.p. + vehicle p.o.), P < .02                 ALT = Alanine Aminotransferase                                                AST = Aspartate Aminotransferase                                              LDH = Lactate Dehydrogenase                                                   CPK = Creatine Phosphokinase                                                  SDH = Sorbitol Dehydrogenase                                             

Example 5 Uridine Reduces Tissue Damage in Mice Treated With CarrageenanAs A Potentiator of Endotoxin Toxicity

Carrageenan is a polysaccharide derived from seaweed which modifies theactivity of macrophages, which are principal cellular mediators ofsystemic inflammatory response to endotoxin. Macrophages releaseinflammatory peptides and other compounds in response to endotoxin.Carrageenan pretreatment sensitizes macrophages so that much lessendotoxin than normal is required to elicit a serious systemicinflammatory response. Furthermore, a somewhat different spectrum ofinflammatory mediators is involved in the toxic effects of thecombination of carrageenan plus endotoxin compared to endotoxin alone(Franks et al., Infection and Immunity, 59:2609-2614 1991!). The purposeof this experiment was to determine the effect of uridine on tissuedamage induced by a combination of carrageenan and endotoxin.

Methods:

Female Balb/C mice (eight weeks old) were divided into five groups ofsix animals each. One group of animals remained untreated to providebasal values for serum chemistry indices of tissue damage. Mice in theother four groups received 2 mg of lambda carrageenan in 0.2 ml salineby i.p. injection; three of these groups also received, one hour later,2 micrograms of Salmonella typhimurium endotoxin, also by i.p. injectionin a volume 0.2 ml saline. Two of the groups that received bothcarrageenan and endotoxin also received uridine (2000 mg/kg i.p. in 0.2ml saline); one group was treated with uridine 30 minutes afteradministration of endotoxin, and the other received 3 uridinepretreatments, 24, 6, and 2 hours before endotoxin administration, at2000 mg/kg/dose i.p. Eighteen hours after endotoxin administration,blood samples were collected for determination of serum chemistry valuesof indicators of tissue damage.

Results:

The combination of carrageenan with a low dose of endotoxin (2 mg)resulted in significant tissue damage as evaluated by serum chemistryindices. Treatment with uridine either before or after administration ofendotoxin resulted in significant attenuation of tissue damage due tothe carrageenan-endotoxin combination. Data are shown below.

                                      TABLE 3                                     __________________________________________________________________________    Uridine attenuates endotoxin-induced tissue damage in carrageenan-sensitiz    ed mice                                                                              ALT    AST    LDH    CPK     SDH                                       __________________________________________________________________________    Basal (No LPS)                                                                       223 ± 77                                                                          141 ± 35                                                                          700 ± 145                                                                         747 ± 278                                                                          33 ± 1                                 Control (LPS)                                                                        1937 ± 235                                                                        2072 ± 149                                                                        7360 ± 354                                                                        11612 ± 1513                                                                       107 ± 17                               Uridine                                                                               817 ± 202*                                                                        989 ± 139*                                                                       4385 ± 454*                                                                        5485 ± 1638*                                                                       80 ± 12*                              Uridine                                                                               770 ± 141*                                                                       891 ± 79*                                                                         4416 ± 283*                                                                       5033 ± 565*                                                                        117 ± 9                                (postreatment)                                                                __________________________________________________________________________     * = Different from Control, P < .05                                           ALT = Alanine Aminotransferase                                                AST = Aspartate Aminotransferase                                              LDH = Lactate Dehydrogenase                                                   CPK = Creatine Phosphokinase                                                  SDH = Sorbitol Dehydrogenase                                             

Example 6 Uridine Improves Survival in Zymosan-treated Mice

Purpose:

Zymosan is a yeast component, primarily polysaccharide, which inducessystemic inflammation and activation of complement. In fungal infectionsin general (including but not limited to yeast infections), suchpolysaccharides participate in the induction of a sepsis response.Zymosan administration to rodents is considered to be a suitable modelfor multiple organ failure syndrome (Goris et al. (1986) Arch. Surg.121:897-901; Steinberg et al. (1989) Arch. Surg. 124:1390-1395).Mortality at minimum lethal doses of zymosan is due in part to gutdamage leading to translocation of bacteria and bacterial toxins fromthe gut into the bloodstream (Deitch et al., (1992) J. Trauma32:141-147).

Methods:

Female Balb/C mice (eight weeks old) were divided into groups of fiveanimals each:

1. Zymosan 15 mg

2. Zymosan 15 mg+Uridine

3. Zymosan 20 mg

4. Zymosan 20 mg+Uridine

5. Basal

Zymosan A was suspended in mineral oil at a concentration of 50 mg/mland administered by intraperitoneal injection. Uridine (2000 mg/kg) wasadministered by intraperitoneal injection in a volume of 0.2 ml twohours before administration of Zymosan.

18 hours after administration of Zymosan, blood samples were collectedfrom both groups of mice that received 20 mg Zymosan and from a basal(untreated) group for subsequent measurement of serum chemistry indicesof tissue damage.

Results:

    ______________________________________                                        Group               Survival                                                  ______________________________________                                        A. Surviva1 at 48 hours:                                                      Zymosan 15 mg/kg    0/5                                                       Zymosan 15 mg/kg + Uridine                                                                        5/5                                                       Zymosan 20 mg/kg    0/5                                                       Zymosan 20 mg/kg + Uridine                                                                        3/5                                                       B. Survival at 14 days (complete recovery)                                    Zymosan 15 mg/kg    0/5                                                       Zymosan 15 mg/kg + Uridine                                                                        4/5                                                       ______________________________________                                    

Uridine significantly improved survival time and incidence of long-termsurvivors among mice treated with Zymosan.

C. Serum Chemistry Indices of Tissue Damage

                  TABLE 4                                                         ______________________________________                                        Uridine attenuates Zymosan-induced tissue damage                              ALT         AST      LDH       CPK     SDH                                    ______________________________________                                        Basal  50 ± 22                                                                             93 ± 41                                                                              899 ± 198                                                                         532 ± 731                                                                          52 ± 25                           Zymosan                                                                              397 ± 140                                                                           392 ± 97                                                                            1974 ± 392                                                                         2107 ± 1172                                                                        81 ± 15                           Zymosan                                                                              120 ± 126                                                                           273 ± 131                                                                           1419 ± 244                                                                         754 ± 370                                                                          58 ± 22                           Uridine                                                                       ______________________________________                                         ALT = Alanine Aminotransferase                                                AST = Aspartate Aminotransferase                                              LDH = Lactate Dehydrogenase                                                   CPK = Creatine Phosphokinase                                                  SDH = Sorbitol Dehydrogenase                                             

Example 7 Comparison of Effects of Uridine Versus Arginine on Survivalof Endotoxin-treated Mice

Purpose:

The amino acid arginine is reported to have beneficial effects in sepsissyndrome (Leon et al. J. Parenteral and Enteral Nutrition, 1991,15:503-508). The purpose of this study was to compare the efficacy ofuridine with that of arginine, an agent which supports liver function insepsis syndrome and which is clinical use for this purpose.

Methods:

Female Balb/C mice weighing 25 grams were divided into five groups offive or six animals each. Mice in the remaining five groups received 125micrograms of Salmonella typhimurium endotoxin (LPS) by i.p. injectionin a volume 0.2 ml saline. Two hours prior to endotoxin administration,the five groups of mice received injections of:

1) Saline (Controls)

2) Uridine 2000 mg/kg

3) Arginine 25 mg/kg

4) Arginine 250 mg/kg

5) Arginine 1250 mg/kg

All drugs were administered i.p. in 0.2 ml saline. The numbers ofsurviving mice in each group were determined 16, 20, and 24 hours.

Results:

Only one of the Control animals was alive 16 hours after LPS; incontrast, the majority of the animals treated with uridine or argininewere alive at this point. However, by 24 hours after administration ofendotoxin, the only surviving animals were in the group treated withuridine. All three doses of arginine did improve survival time (but didnot produce any long-term survivors), and the lowest dose (25 mg/kg) wasmore effective than the highest dose (1250 mg/kg). Uridine was clearlymore effective than arginine in promoting survival of endotoxin-treatedanimals.

                  TABLE 5                                                         ______________________________________                                        Effect of uridine vs arginine on survival after LPS administration                     Time after LPS (hr)                                                  Groups     16            20     24                                            ______________________________________                                        1. Control 1/6           0/6    0/6                                           2. Uridine 5/5           5/5    5/5                                           3. Arg 25  5/5           3/5    0/5                                           4. Arg 250 4/5           2/5    0/5                                           5. Arg 1250                                                                              4/6           1/6    0/6                                           ______________________________________                                    

Example 8 Orotic Acid Improves Survival of Mice Treated With Salmonellatyphimurium Endotoxin

Purpose:

Sepsis syndrome caused by gram-negative bacteria is mediated primarilythrough endotoxin, a lipopolysaccharide constituent of the bacterialwall. The purpose of this experiment was to determine the effect oforotate on survival of mice treated with a lethal dose of purifiedSalmonella typhimurium endotoxin.

Methods:

Twenty female Balb/C mice (eight weeks old) were divided into two groupsof ten animals each. One group of mice received four treatments withlysine orotate (200 mg/kg/dose; 9 AM and 2 PM on each of two consecutivedays). Lysine orotate is a water-soluble salt of orotic acid; lysinealone does not improve survival of endotoxin-treated mice. Controlanimals received 0.2 ml of sterile water on the same treatment schedule.All mice received 100 micrograms of Salmonella typhimurium endotoxin(LPS) by intraperitoneal injection in 0.2 ml of saline immediately afterthe last dose of lysine orotate. Survival was monitored for one week.

Results:

All of the mice in the Control group died within 48 hours. Nine of theten mice treated with Lysine Orotate survived the full 72 hourobservation period and were still alive and appeared to recovercompletely one week after LPS administration.

                  TABLE 6                                                         ______________________________________                                        Orotate improves survival of endotoxin-treated mice                                    Survival after endotoxin treatment                                   Time (hr after LPS)                                                                      24     26       28   32     48   72                                ______________________________________                                        Control     6/10   4/10     3/10                                                                               2/10  0/10 0/10                              LOR        10/10  10/10    10/10                                                                              10/10  9/10 9/10                              ______________________________________                                    

Example 9 Orotic Acid Protects Tissues Against Endotoxin Damage

Purpose:

The purpose of this study was to demonstrate the protective effect oforotic acid in prevention of inflammatory tissue damage caused byendotoxin.

Methods:

Female Balb/C mice (eight weeks old) were divided into three groups ofsix animals each. One group of animals remained untreated to providebasal values for serum chemistry indices of tissue damage. Mice in theremaining two groups received 100 micrograms of Salmonella typhimuriumendotoxin (LPS) by i.p. injection in a volume 0.2 ml saline. Two hoursprior to endotoxin administration, mice in one group received lysineorotate in a dose corresponding to 100 mg/kg of free orotic acid.Eighteen hours after endotoxin administration, blood samples werecollected for determination of serum chemistry content of indicators oftissue damage.

Results:

Orotate protected tissues against damage from endotoxin administration.

                                      TABLE 7                                     __________________________________________________________________________    Orotate attenuates endotoxin-induced tissue damage                                   ALT    AST    LDH    CPK    SDH                                        __________________________________________________________________________    Basal (No LPS)                                                                       132 ± 14                                                                          165 ± 21                                                                          681 ± 552                                                                         1258 ± 233                                                                        42 ± 1                                  Control (LPS)                                                                        2827 ± 413                                                                        2860 ± 506                                                                        6833 ± 1167                                                                       6820 ± 365                                                                        680 ± 142                               Orotate + LPS                                                                         252 ± 99*                                                                        415 ± 77*                                                                         1641 ± 274*                                                                       1040 ± 283*                                                                       89 ± 7*                                 __________________________________________________________________________     * = Different from Control (LPS i.p.) P < .02                                 ALT = Alanine Aminotransferase                                                AST = Aspartate Aminotransferase                                              LDH = Lactate Dehydrogenase                                                   CPK = Creatine Phosphokinase                                                  SDH = Sorbitol Dehydrogenase                                             

Example 10 Uridine and Triacetyluridine Attenuate Hepatic Damage Causedby Concanavalin A

Purpose:

Interleukin-2 (IL-2) is used clinically for treatment of severalvarieties of cancer. Hepatic toxicity in response to IL-2, is notuncommon in patients receiving therapeutic doses of IL-2 for cancertreatment (Viens et al., J. Immunother. 1992 11:218-24). In anexperimental model of autoimmune hepatitis induced by administration ofConcanavalin A (Con A) to mice, hepatic damage is reported to be relatedto elevated production of endogenous IL-2 (Tiegs et al., J. Clin.Invest. 1992 90:196-203). The purpose of this study was to demonstratethe utility of the compounds and methods of the invention in attenuatinghepatic damage initiated by administration of Con A.

Methods:

Female Balb/C mice (eight weeks old) were divided into four groups offive animals each. One group of animals remained untreated to providebasal values for serum chemistry indices of tissue damage. Mice in theremaining three groups received 10 mg/kg Concanavalin A by intravenous(tail vein) injection in a volume of 0.2 ml saline. Two hours prior toreceiving Con A, one of these groups of mice received uridine (2000mg/kg i.p. in 0.2 ml saline) and another group received triacetyluridine(6000 mg/kg orally, in 0.6 ml of a 1:1 corn oil/water emulsioncontaining 2.5% Tween 80); the remaining Con A-treated group (Control)received 0.2 ml saline i.p. two hours prior to Con A. Twenty hours afteradministration of Con A, blood samples were collected from all mice fordetermination of serum levels of various indices of tissue damage ormetabolic dysfunction.

Results:

Con A administration resulted in significant damage to the liver, asassessed by serum levels of the enzymes ALT, AST, and SDH. Con A did notsignficantly elevate levels of creatine phosphokinase (CK), an enzymefound primarily in muscle; tissue damage due to Con A in this model ismore specifically localized in the liver than is damage due toendotoxin. Uridine and TAU both reduced the liver damage produced by ConA administration, as shown in Table 8 below.

                                      TABLE 8                                     __________________________________________________________________________    Uridine and Triacetyluridine attenuate liver damage caused by                 Concanavalin A                                                                        ALT    AST   LDH   CPK   SDH                                          __________________________________________________________________________    Basal (No Con A)                                                                      144 ± 18                                                                          217 ± 27                                                                         790 ± 90                                                                         2392 ± 370                                                                       51 ± 2                                    Con A   2652 ± 847                                                                        2765 ± 1030                                                                      4335 ± 1385                                                                      2572 ± 486                                                                       1114 ± 318                                Con A + Uridine                                                                        289 ± 115*                                                                        394 ± 114*                                                                       973 ± 202*                                                                      1996 ± 317                                                                        163 ± 68*                                Con A + TAU                                                                            575 ± 286*                                                                       613 ± 221                                                                        1380 ± 270                                                                       1951 ± 435                                                                        283 ± 143*                               __________________________________________________________________________     * = Different from Control (LPS i.p.), P < .02                                ALT = Alanine Aminotransferase                                                AST = Aspartate Aminotransferase                                              LDH = Lactate Dehydrogenase                                                   CPK = Creatine Phosphokinase                                                  SDH = Sorbitol Dehydrogenase                                             

Liver damage in the Con A model used in this study is related toelevated IL-2 levels, and is mediated through T lymphocytes. Therefore,the compounds and methods of the invention are useful in reducing sideeffects due to therapeutic administration of IL-2; furthermore, thecompounds and methods of the inventions are useful in treatingautoimmune hepatitis.

Example 11 Uridine Attenuates Sepsis Induced Alterations in BloodCoagulation

Purpose:

Disseminated Intravascular Coagulation (DIC) is a serious consequence ofsepsis, in which both blood coagulation and fibrinolysis are activated,so that blood clotting factors are rapidly consumed. DIC can result inhemorrhage or thrombus formation. The liver is the primary site forsynthesis of clotting factors and for clearing micro-aggregates ofthrombin from the circulation. This purpose of this experiment was todetermine the effect of pyrimidine nucleotide precursors on coagulationdisorders induced by sepsis. Partial thromboplastin time was used as anindex of the status of the blood coagulation system.

Methods:

Thirty female Balb/C mice (eight weeks old) were divided into threegroups of ten animals each. One group of mice remained untreated, andwas used to determine basal values for partial thromboplastin time. Twogroups of mice received received 30 mg/kg killed E. coli (strain0111:B4); Two hours before E. coli administration, one group receiveduridine (2000 mg/kg) by intraperitoneal injection. 20 hours after E.coli administration, plasma samples were collected from all thirty micefor determination of partial thromboplastin time (PTT). 0.27 ml of bloodwas collected via the retro-orbital plexus into a tube containing 0.03ml of 3.5% sodium citrate, pH 4. Plasma was separated by centrifugation,and 100 microliters of plasma was transferred to a clean 1.5 mlEppendorf tube for determination of PTT with a commercial kit.

Results:

Administration of killed E. coli resulted in a prolongation of thenormal partial thromboplastin time. Uridine attenuated thesepsis-induced change in coagulation time, as shown in Table 9.

                  TABLE 9                                                         ______________________________________                                        Uridine attenuates sepsis-induced alterations in partial thromboplastin       time                                                                          Partial Thromboplastin Time                                                   Group          PTT (seconds)                                                  ______________________________________                                        Basal (Normal) 32.3 ± 1.3                                                  E. Coli        69.8 ± 5.4                                                  E. Coli + Uridine                                                                              51.2 ± 2.1 *                                              ______________________________________                                         * = different from control (E. Coli alone) value, P < .05                

Example 12 Combined Liver Injury Due to T cells and Endotoxin

Several important forms of viral hepatitis as well as autoimmunehepatitis are initiated by cytotoxic T cells which attack hepatocytesbearing appropriate vital or other antigens. Since endotoxinparticipates in liver damage initiated by a number of other agents likecarbon tetrachloride, choline deficiency, ethanol, or cholestasis,studies were conducted to determine whether liver injury caused by Tcells induces hepatic hypersensitivity to endotoxin. Following thisexperiment, the effect of TAU on combined liver injury due to both Tlymphocytes and endotoxin was investigated.

Example 12A Concanavalin A Potentiates Endotoxin-induced Tissue Damage

Groups (n=6) of female Balb/C mice, age eight weeks, receivedConcanavalin A (2.5 mg/kg i.v.), endotoxin (Salmonella typhimurium, 0.5mg/kg), or a combination of Con A and endotoxin. The Con A wasadministered twenty four hours before endotoxin. Blood samples weretaken 18 hours after injection of endotoxin (or its vehicle in thegroups of mice that did not receive endotoxin). The "Basal" group ofmice received vehicle only (saline) instead of Con A or endotoxin.

                                      TABLE 1                                     __________________________________________________________________________    Concanavalin A potentiates endotoxin-induced tissue damage                            ALT   AST   LDH    CPK   SDH                                          __________________________________________________________________________    Basal    87 ± 15                                                                         110 ± 9                                                                          656 ± 41                                                                          413 ± 87                                                                         39 ± 2                                    Con A 2.5 mg/kg                                                                       117 ± 19                                                                         170 ± 16                                                                         915 ± 46                                                                           419 ± 132                                                                       42 ± 4                                    LPS 0.5 mg/kg                                                                         119 ± 23                                                                         256 ± 22                                                                         881 ± 10                                                                          426 ± 82                                                                         41 ± 3                                    Con A + LPS                                                                           1130 ± 494                                                                       2119 ± 910                                                                        4370 ± 1303                                                                      1525 ± 450                                                                        471 ± 267                                __________________________________________________________________________     ALT = Alanine Aminotransferase                                                AST = Aspartate Aminotransferase                                              LDH = Lactate Dehydrogenase                                                   CPK = Creatine Phosphokinase                                                  SDH = Sorbitol Dehydrogenase                                             

Endotoxin or Con A alone at the doses used in this experiment producedminimal damage to liver and muscle as determined by serum enzyme levels(ALT, AST, LDH and SDH are markers for liver damage; CPK is an indicatorfor muscle damage). However, in mice treated with the combination of ConA and endotoxin, significantly greater damage was observed. The toxicityof Con A in this model is believed to be specifically related to TLymphocyte-mediated liver damage (Tiegs et al., J. Clin. Invest.90:196-203, 1992). Therefore, these results support the view thatenterally-derived endotoxin participates in liver damage attributed tocytotoxic T lymphocytes (i.e. in viral and autoimmune hepatitis), as hasbeen demonstrated for liver damage initiated by other primary insultsincluding carbon tetrachloride, choline deficiency, D-galactosamine, andviral infections.

Example 12B TAU Attenuates Combined Liver Injury Due to CTL's andEndotoxin

Experimental hepatitis initiated by intravenous administration ofconcanavalin A (Con A) is mediated by activation of cytoxic Tlymphocytes. Liver injury in this model results in a marked increase insensitivity to toxic effects of bacterial endotoxin. Sequentialadministration of Con A and endotoxin results in greater-than-additivehepatic injury (see Example 12 A). Hepatocyte injury in viral andautoimmune hepatitis involves similar mechanisms, with damage initiatedby T cells and exacerbated by enterally-derived endotoxin and otherinflammatory processes.

TAU protects the liver of experimental animals from damage initiated byeither endotoxin or Con A. In this experiment, TAU was tested forhepatoprotective effects in mice subjected to combined liver injurycaused by sequential administration of both Con A and endotoxin.

Methods:

Female Balb/C mice (eight weeks old) were divided into three groups ofseven animals each. One group of animals remained untreated to providebasal values for serum chemistry indices of tissue damage. Mice in theremaining two groups received 2 mg/kg Concancavalin A by intravenous(tail vein) injection in a volume of 0.2 ml saline, followed 24 hourslater by Salmonella typhimurium endotoxin (10 micrograms i.p..). One ofthese groups of mice received TAU (6000 mg/kg orally, in 0.6 ml of 0.5%methylcellulose two hours before Con A and again 2 hours beforeendotoxin; the remaining Con A/endotoxin-treated group (Control)received vehicle (methylcellulose) alone. Eighteen hours afteradministration of endotoxin, blood samples were collected from all micefor determination of serum levels of various indices of tissue damage ormetabolic dysfunction.

Results:

Sequential administration of Con A and endotoxin resulted in significantliver injury, as assessed by serum chemistry indices of liver damage.TAU, administered orally, markedly attenuates this combined liverinjury.

    __________________________________________________________________________    Oral TAU attenuates liver damage caused by Concanavalin A + LPS                        ALT   AST   LDH    CPK   SDH                                         __________________________________________________________________________    Basal    118 ± 33                                                                         162 ± 14                                                                         522 ± 80                                                                          1521 ± 235                                                                       56 ± 3                                   Con A/LPS                                                                              2295 ± 309                                                                       3408 ± 389                                                                       5696 ± 560                                                                        4684 ± 1569                                                                      700 ± 69                                 Con A/LPS + TAU                                                                         285 ± 67*                                                                        451 ± 87*                                                                        1341 ± 236*                                                                      2098 ± 465*                                                                       122 ± 19*                               __________________________________________________________________________     *= Different from Control (LPS i.p.), P < .02                                 ALT = Alanine Aminotransferase                                                AST = Aspartate Aminotransferase                                              LDH = Lactate Dehydrogenase                                                   CPK = Creatine Phosphokinase                                                  SDH = Sorbitol Dehydrogenase                                             

Example 13 Oral Triacetyluridine Improves Recovery From EthanolIntoxication

Ethanol intoxication results in depression of activity in the centralnervous system. Recovery is dependent upon clearance of ethanol from thesystem. Ethanol clearance from the circulation occurs primarily in theliver, regulated by both the enzyme alcohol dehydrogenase and the redoxbalance and metabolic state of the liver.

In these experiments, ethanol-intoxicated mice were treated withtriacetyluridine (TAU) in order to determine whether metabolic supportthrough provision of uridine to the liver and other tissues affectedrecovery from ethanol intoxication.

Experiment 1: Fasted Mice

Methods:

Female Balb/C mice weighing an average of 22 grams were fasted for 24hours. 9 mice received oral TAU 2000 mg/kg p.o., and 8 received vehicle(0.75% Hydroxypropylmethylcellulose in water).

One hour later, all animals received 5.7 ml/kg ethanol (0.5 ml of 25%aqueous solution p.o.).

One hour after EtOH, mice received an additional dose of TAU or vehicle.All mice were basically comatose at this time.

Behavior was monitored at hourly intervals, beginning 3 hours afterethanol administration. The scale for behavioral assessment is asfollows:

Behavioral Recovery After Ethanol Intoxication

Deep coma: Unresponsive to stimuli. Slow respiration

Prostrate: Mice laying flat but not moving. Eyelid reflex to touchingwith a probe. Rapid respiration.

Righting reflex: When placed on its back, animal attempts to turn overwithin 5 seconds. Category includes all "mobile" animals and some"prostrate".

Mobile: Animal is capable of walking.

    ______________________________________                                        TAU accelerates recovery from ethanol intoxication in fasted mice             Time  Dead    Deep coma Prostrate                                                                            Righting Reflex                                                                         Mobile                               ______________________________________                                        Control n = 8 mice                                                            3 hr  1       8         0      0         0                                    4 hr  1       5         3      0         0                                    5 hr  2       3         3      3         0                                    6 hr  2       2         2      4         2                                    7 hr  2       1         1      4         4                                    8 hr  2       1         1      5         4                                    TAU n = 9 mice                                                                3 hr  0       5         4      4         0                                    4 hr  0       4         5      4         0                                    5 hr  0       2         7      6         0                                    6 hr  0       1         1      7         7                                    7 hr  0       1         0      8         8                                    8 hr  0       0         1      8         8                                    ______________________________________                                         Mice = Female Balb/C, 22 grams, fasted 24 hours                               Ethanol dose = 5.7 ml/kg p.o. at time = 0 hr (0.7 ml of 25% EtOH)             TAU (2 g/kg) or vehicle (control group) were administered one hour before     and one hour after ethanol                                               

Experiment 2: Non-fasted Mice

Female Balb/C mice weighing an average of 22 grams were al;lowed freeaccess to food up to the time of the experiment. 10 mice received oralTAU 2000 mg/kg p.o., and 10 received vehicle (0.75% HPMC).

One hour later, all animals received 8 ml/kg ethanol (0.7 ml of 25%aqueous solution p.o.).

One hour after EtOH, mice received an additional dose of TAU or vehicle.

Behavior was monitored at intervals of 2,3,4, and 6 hours after ethanoladministration. The scale for behavioral assessment was the same as inthe test on fasted mice above.

    ______________________________________                                        TAU accelerates recovery from ethanol intoxication in non-fasted mice         Time  Dead    Deep coma Prostrate                                                                            Righting Reflex                                                                         Mobile                               ______________________________________                                        Control n = 10 mice                                                           2 hr  0       9         1      0         0                                    3 hr  0       7         3      2         0                                    4 hr  1       1         6      5         2                                    6 hr  1       0         1      8         8                                    TAU n = 10 mice                                                               2 hr  0       5         5      2         0                                    3 hr  0       1         5      5         3                                    4 hr  0       0         3      8         7                                    6 hr  0       0         0      10        10                                   ______________________________________                                         Mice = Female Balb/C, 22 grams, fed ad libitum                                Ethanol dose = 8 ml/kg p.o. at time = 0 hr (0.7 ml of 25% EtOH)               TAU (2 g/kg) or vehicle (control group) were administered one hour before     and one hour after ethanol                                               

TAU clearly improved behavioral recovery in mice subjected to severeethanol intoxication. Non-fasted mice were given a higher dose ofethanol than fasted animals (8 ml/kg versus 5.7 ml/kg), but neverthelessrecovered somewhat faster. This observation highlights the importance ofenergy metabolism in recovery from ethanol intoxication. TAU acceleratesrecovery from ethanol intoxication in both fed and fasted animals.

Example 14 Triacetyluridine Reduces Mortality in Viral Hepatitis in Mice

Frog virus 3 (FV3) induces a rapidly fatal hepatitis in mice, which ismediated in part by secondary damage due to endogenous endotoxin (Gut etal., J. Infect. Disease., 1984, 149:621).

Triacetyluridine (TAU) was tested in this model to demonstrate that thisagent and other compounds of the invention have useful therapeuticeffects in viral hepatitis.

Methods:

Lyophilized FV3 was reconstituted in phosphate-buffered saline to adensity of 1×10⁸ plaque-forming units (PFU) per ml.

Female Balb/C mice weighing 25 grams received FV3 virus at dosescorresponding to the approximated LD₅₀ by intraperitoneal or intravenous(tail vein) injection. TAU (3000 mg/kg) or vehicle (0.75hydroxypropylmethylcellulose) was administered orally one hour beforeFV3 and on subsequent afternoons and mornings. Animals were observed forthree days; the animals that did not survive this observation period alldied approximately 24-30 hours after virus administration.

    ______________________________________                                                    Survival                                                          ______________________________________                                        Intraperitoneal administration of FV3                                         Virus: FV3 4 × 10.sup.7 PFU/mouse i.p.                                          Control                                                                              6/10                                                                   TAU   10/10                                                           Intravenous administration of FV3                                             Virus: FV3 2 × 10.sup.7 PFU/mouse i.v.                                          Control                                                                              5/10                                                                   TAU   10/10                                                           ______________________________________                                    

The foregoing is intended as illustrative of the present invention butnot limiting. Numerous variations and modifications may be effectedwithout departing from the true spirit and scope of the invention.

What is claimed is:
 1. A method for treating tissue damage due tosystemic inflammatory response syndrome comprising administering to ananimal a therapeutically effective amount of uridine, cytidine, oroticacid, acylated uridine, acylated cytidine, or acylated orotic acid, or apharmaceutically acceptable salt thereof.
 2. The method of claim 1wherein said acylated uridine is triacetyluridine.
 3. The method ofclaim 1 further comprising administering an inhibitor of uridinephosphorylase.
 4. A method for preventing tissue damage due to systemicinflammatory response syndrome comprising identifying an animal at riskfor developing tissue damage due to systemic inflammatory responsesyndrome, and then administering to said animal a prophylacticallyeffective mount of uridine, cytidine, orotic acid, acylated uridine,acylated cytidine, acylated orotic acid, or a pharmaceuticallyacceptable salt thereof.
 5. The method of claim 4 wherein said acylateduridine is triacetyluridine.
 6. The method of claim 4 further comprisingadministering an inhibitor of uridine phosphorylase.
 7. A method fortreating sepsis comprising administering to an animal a therapeuticallyeffective amount of uridine, cytidine, orotic acid, acylated uridine,acylated cytidine, or acylated orotic acid.
 8. The method of claim 7wherein said acylated uridine is triacetyluridine.
 9. The method ofclaim 7 further comprising administering an inhibitor of uridinephosphorylase.
 10. A method for preventing sepsis comprising identifyingan animal at risk for developing sepsis, and then administering to saidanimal aprophylactically effective amount of uridine, cytidine, oroticacid, acylated uridine, acylated cytidine, or acylated orotic acid. 11.The method of claim 10 wherein said acylated uridine istriacetyluridine.
 12. The method of claim 10 further comprisingadministering an inhibitor of uridine phosphorylase.
 13. A method fortreating sepsis comprising administering to an animal a therapeuticallyeffective amount of an inhibitor of uridine phosphorylase.
 14. A methodfor preventing sepsis comprising identifying an animal at risk fordeveloping sepsis, and then administering to said animal aprophylactically effective amount of an inhibitor of uridinephosphorylase.
 15. A method for reducing toxicity of a therapeuticcytokine or inflammatory stimulus comprising administering to a animal atherapeutically effective mount of uridine, cytidine, orotic acid,acylated uridine, acylated cytidine, acylated orotic acid, or apharmaceutically acceptable salt thereof, prior to, during, or afteradministration of said cytokine or said stimulus.
 16. The method ofclaim 15 wherein said acylated uridine is triacetyluridine.
 17. Themethod of claim 15 further comprising administering an inhibitor ofuridine phosphorylase.
 18. The method of claim 15 wherein said cytokineor said stimulus is selected from the group consisting of interleukin-1,interleukin-2, interleukin-6, tumor necrosis factor, endotoxin, fungalpolysaccharides, and double-stranded RNA.
 19. The method of claim 18wherein said cytokine or said stimulus is selected from the groupconsisting of interleukin-1, interleukin-2, interleukin-6, tumornecrosis factor, endotoxin, fungal polysachharides, and double-strandedRNA.
 20. A method for reducing toxicity of a therapeutic cytokine orinflammatory stimulus comprising administering to an animal atherapeutically effective amount of an inhibitor of uridinephosphorylase prior to, during, or after administering said cytokine orsaid stimulus.